In 1996, McConnell signed a statement supporting a constitutional amendment to ban abortion, which read, "Abortion kills 1.5 million innocent human beings in America every year...We believe that the abortion license is a critical factor in America's virtue deficit."[7]

As a respected constitutional scholar during his law school tenure, McConnell contended that originalism is consistent with the Supreme Court's 1954 desegregation decision Brown v. Board of Education, against critics of originalism who argue that they are inconsistent.[8][9] McConnell has likewise argued that the Court's decision in Bolling v. Sharpe was correct, but should have been reached on other grounds, because Congress never "required that the schools of the District of Columbia be segregated."[10]

I imagine that Gov. Bush and his supporters will put on a brave face and defend this decision, but I cannot imagine that there is much joy in Austin tonight. The Supreme Court, with all the prestige of its position in American public life, could have brought closure to this matter. But instead, by straddling the fence, the court has produced a combination of holdings that can please no one.[11]

While sitting on the Tenth Circuit, Judge McConnell wrote scores of judicial opinions. The Supreme Court reviewed four cases in which Judge McConnell wrote an opinion; in each case the Court reached the same result as the opinion by Judge McConnell. First, in O Centro Espirita Beneficiente Uniao do Vegetal v. Ashcroft, 546 U.S. 418 (2006), a case involving the religious use of a hallucinogenic tea, the Supreme Court affirmed 8–0 a Tenth Circuit en banc decision to which Judge McConnell wrote a concurring opinion. Second, in Fernandez-Vargas v. Gonzales, 548 U.S. 30 (2008), a case involving the retroactive application of a statutory provision limiting appeals from immigration removal orders, the Supreme Court affirmed 8–1 a Tenth Circuit panel decision written by Judge McConnell. Third, in Begay v. United States, No. 06–11543 (April 16, 2008), a case involving whether a felony conviction for driving under the influence is a crime of violence for purposes of the Armed Career Criminal Act, the Supreme Court reversed 6–3 a Tenth Circuit panel decision from which Judge McConnell dissented. Fourth, in Pleasant Grove City, Utah v. Summum, No. 07-665 (February 25, 2009), a case involving whether the presence of a Ten Commandments monument on government property gave another religion a First Amendment right to place its own monument on the same property, the Supreme Court unanimously reversed a Tenth Circuit panel decision that Judge McConnell had challenged by writing a dissent from the denial of rehearing en banc.

Significant opinions written by Judge McConnell include the following:

United States v. Patton (2006). Commerce Clause. Writing for the court, McConnell upheld a federal statute prohibiting the possession of body armor by felons. Even though the statute, as applied to Mr. Patton's intrastate and noncommercial possession of body armor, could not be sustained under any of the three Lopez categories established by the Supreme Court, it fell within the Commerce Clause under another line of Supreme Court precedent (Scarborough) and noted the tension between the two sets of precedents. The court also rejected Mr. Patton's due process and necessity claims. The case was covered by Decision of the Day and The Volokh Conspiracy and was the subject of a constitutional law final exam at Cornell.